A motor of this type is for example used for driving a public works machine or the like, such as a loader with four driving wheels. In accordance with the known prior art, this motor forms part of a hydrostatic transmission comprising a pump for supplying the motor, the motor itself, a gear box generally with two speeds, and two axles whose ends are connected to the wheels of the vehicle. The motor is a high-speed motor and its driven shaft is not coaxial with the main shaft of the transmission, with the result that a (transverse) connecting shaft must be provided between the motor and the transmission shaft. The driven shaft of the motor or the connecting shaft meshes on the input of the gear box. At the output, said gear box presents a spur reduction gear connected to the main shaft of the transmission. The gear box makes it possible to obtain two different speed ratios for the main shaft of the transmission but, the motor being a high speed motor, these speeds remain considerable. Consequently, it is necessary to provide a final reduction gear in each of the wheels in order to return the speeds of rotation to usual values.
This type of transmission which comprises a high-speed motor presents several drawbacks. On the one hand, the high-speed hydraulic motor (whose speed of rotation at the output is conventionally included between 2000 and 3000 rpm) is noisy. On the other hand, the motor is offset with respect to the main shaft of the transmission, with the result that the motor and gear box assembly is cumbersome. Finally, the necessity of providing reduction gears in the wheels induces a risk of fragility of the transmission.
It is an object of the present invention to overcome these drawbacks by proposing a motor capable of constituting the motor of a transmission with two speed ranges, which reduces noise and bulk and increases reliability.